Uncrewed Systems Technology 043 l Auve Tech Iseauto taxi l Charging focus l Advanced Navigation Hydrus l UGVs insight l MVVS 116 l Windracers ULTRA l CES 2022 show report l ECUs focus I Distant Imagery

56 Digest | Advanced Navigation Hydrus Advanced Navigation expects that it will be more useful for offloading data while charging. The wireless docking port is likely to be designed with an optical receiver and a tether for power and data running up to the surface. Propulsion The thrusters have been designed in- house, and notably feature hubless propellers (or impellers), with their blade shapes optimised in Ansys CFD software. This is key to ensuring nothing can become tangled in them while underwater, be it rope, seaweed, fish and so on. “As well as being impervious to jamming from things like that, they are a nearly completely sealed design,” Orr says. “The stators are moulded into the plastic, and that makes the thrusters really good in terms of maintenance and life expectancy, because you only have to replace the impellers and bearings. The impeller shrouds can be unscrewed and taken off to allow the hub assembly to be replaced.” The motors have also been designed to run at low minimum speeds, without sacrificing power efficiency. They typically run at around 5 W during operation. Advanced Navigation does not give exact details of its e-motor architecture, save that it is ironless and indeed entirely metal-less in its rotors, and bearings (except for the rare earth magnets). Furthermore, no lubrication – be it oil or seawater – is used, in a notable departure from the hubless thrusters previously featured in this magazine. The ESCs have been designed in-house and are based on an STMicroelectronics design, as with some of the other electronics already discussed. Future plans The combination of subsea data uploads and recharging technology means that Hydrus UUVs could be working routinely as ‘resident’ systems across a wide variety of infrastructures and environments, running daily data capture missions with little need to return to the surface other than occasional anti-fouling treatments or impeller replacements. For users with further requirements on minimising downtime between surveys, a new version of the Hydrus is also in development, with an eye towards longer endurance. Orr comments that engineering it is a straightforward matter: the hull length will be extended to accommodate around 10 times the battery volume, with simulations indicating that manoeuvring and station- holding will be largely unchanged by the increased battery weight. “With our open architecture, we expect to keep developing new software modules with third parties to suit a wide range of applications,” Orr adds. “Given how flexible this vehicle and its capabilities are, we’re looking forward to seeing what different users do with it.” April/May 2022 | Unmanned Systems Technology Dimensions: 470 mm length, 260 mm diameter Weight (in air): 4.7 kg Maximum depth rating: 3000 m Maximum range: 9 km Maximum endurance: 2-3 hours Some key suppliers INS: in-house DVL: in-house USBL: in-house Modems: in-house Transducer ceramics: Steiner & Martins Lithium-ion cells: COTS BMS design: STMicroelectronics Thruster design: in-house Specifications Eight hubless propeller drives circle the midsection of the hull. This design choice minimises their maintenance needs and the risk of jamming from tangled objects